The invention is directed to a process for the production of hard solderable and good adhering metal coatings on ceramic parts by applying a palladium containing alloy and to the resulting compositions.
It is known to produce solderable coatings on ceramic bases by applying metal containing baked on pastes. The adhesion of such layers to the ceramic base, however, in many cases is not sufficient. Besides these coatings for the most part are only solderable with silver containing soft solders, but not with hard solders.
Furthermore, the vapor deposition or sputtering of nickel or nickel alloy coatings with iron or chromium is known for making ceramic parts solderable. In practice, however, it has been found that these nickel superimposed layers are attacked by the hard solders used and dissolved. Palladium-nickel alloys have also been proposed for these purposes. However, because of the toxic properties of nickel, nickel and nickel alloys are undesired as vapor deposition or sputter coatings.
Therefore it was the problem of the present invention to find a process for the production of solderable metal coatings on ceramic bases which are resistant to hard solders, have good adhesion to the base and above all are non-toxic.